Constraints on a split superconducting transition under uniaxial strain in Sr₂RuO₄ from scanning SQUID microscopy

Journal Article · 04 October 2023 · Physical Review. B

DOI: https://doi.org/10.1103/PhysRevB.108.144501 · OSTI ID:2001270

Mueller, Eli ^[1]; Iguchi, Yusuke ^[1]; Watson, Christopher ^[2]; Hicks, Clifford ^[3]; Maeno, Yoshiteru ^[4]; Moler, Kathryn A. ^[1]

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1. SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford University, CA (United States)
2. SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
3. Max Planck Institute for the Chemical Physics of Solids, Dresden (Germany); University of Birmingham (United Kingdom)
4. Kyoto University (Japan)

More than two decades after the discovery of superconductivity in Sr₂RuO₄, it is still unclear whether the order parameter has a single component or two degenerate components. For any two-component scenario, application of uniaxial strain is expected to lift the degeneracy, generating two distinct phase transitions. The presence of a second (lower-temperature) transition may be observable by probes that are sensitive to changes in the London penetration depth, λ, as a function of temperature, T. Furthermore, we use scanning SQUID microscopy combined with a uniaxial strain device to test for a second transition under strain. We only observe a single transition. Within the temperature range where a second transition has been suggested by μSR measurements, we further place a tight upper bound of less than 1% on the change in the zero temperature superfluid density n_s ∝ λ^–2 (0) due to a second transition, suggesting that such a transition does not occur. These results constrain theories of the order parameter in Sr₂RuO₄.

• Research Organization: Stanford Univ., CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE); JSPS KAKENHI
• Grant/Contract Number: AC02-76SF00515; JP22H01168
• OSTI ID: 2001270
• Journal Information: Physical Review. B, Vol. 108, Issue 14; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English